(1) Field of the Invention
The present invention relates to a turbine engine component having a leading edge cooling system which is desensitized to the effects of Coriolis forces.
(2) Prior Art
In cooling high thermal load leading edges for turbine high pressure blades, coolant flow is usually supplied by a feed cavity to the blade leading edge. Usually, coolant flow passes through a series of cross-over holes for impingement onto the internal surface of the blade. The impingement heat transfer along with film protection at the leading edge are the traditional heat transfer mechanisms for cooling the blade leading edge. As the blade rotates, the rotational heat transfer in certain areas of the feed cavity may increase at the trailing side of the cavity and decrease on the leading side of the cavity. As the blade rotates, a pressure gradient is set inside the passage to balance the in-plane Coriolis forces. The flow tends to move from the leading side towards the trailing side. On the leading side, the radial velocity profile is gradual in comparison with the profile at the trailing side. In this case, the radial velocity profile is attached to the airfoil walls at the trailing side leading high shear stresses and correspondingly high heat transfer coefficients. The opposite is verified for the leading side of the cooling flow passage. Therefore, the coolant flow in the feed passage experiences forces that create crosswise circulation cells. These cells are large vortices in the main bulk region and smaller Goertier type vertices close to the trailing side. The direct implication of these flow disturbances is the uneven heat pick-up inside the feed cavity.
In general, the external heat flux profile attains the highest values at the blade leading edge. To overcome this thermal load situation, with potential uneven heat pick-up due to Coriolis forces, it is necessary to desensitize the cooling system.